Heat Island Effect causes cities to get much warmer than their surrounding rural landscapes.

Increasing heat awareness among all Californians is important, including for those living in cities, where 94% of Californians live. Great numbers of urban residents also lack reliable access to air conditioning or lack the funds to run the air conditioning.

City heat, summer and urban young man drinking water.

Follow these tips to help protect yourself from heat illness:

What is the heat-island effect and how does it put urban residents more at risk?

Urban areas are typically about 1-7 degrees hotter than outlying areas. Cities tend to get much warmer than their surrounding rural landscapes because they have more dark surfaces, such as unshaded roads and buildings, that gain heat during the day and radiate that heat into the surrounding air.

Cities can have more tall buildings that block wind flow and speed up evaporation. They can also block the heat from being released and trap more of it where humans can feel it.

Air quality worsens on hot, sunny days. Densely populated urban areas concentrate heat-emitting devices, like cars and air conditioners, over small areas. All of this creates smog, a harmful air pollutant, putting these populations at greater risk from hotter temperatures and air pollution. Overall, this contributes to higher air temperatures in cities.

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